1. Field of the Invention
The present invention relates to solvent extracting apparatus and, more particularly, to a single-stage, multiple-processing-station, extracting apparatus in which solvent and miscella of varying strength are applied to the material to be processed at each of the stations and then the processed material removed.
2. Prior Art
The percolation type of solvent extraction apparatus to which the present invention pertains, generally utilize a plurality of baskets in which the material from which oil is to be removed is contained. These baskets are then moved through a solvent and miscella distribution system which distributes the solvent and miscella over the surfaces of the material in the baskets and then collects the enhanced miscella from beneath a screened or perforated plate partition in the bottom of the baskets.
Such a device is illustrated, for example, in Depmer U.S. Pat. No. 3,131,202. In this type of device the material is placed in a plurality of segments in a cylindrical container with the segments forming baskets in the container. The bottom surface of the container is stationary, while the remainder of the cyclindrical container is rotated under a stationary miscella distribution system which applies the miscella to the surface of the material in the rotating baskets. The enhanced miscella then drains through the screen in the bottom of the baskets and is collected for recirculation or subsequent treatment. This type of device requires substantial power to rotate the heavy cylindrical containers which are filled with the material being processed and also tend to cause some vibration of the material which releases fines that enters into the miscella and detrimentally affects the recovery process.
One means of overcoming these difficulties has been provided by the type of apparatus disclosed, for example, in Upton U.S. Pat. No. 3,021,201. In this device the cylindrical container, which is segmented into a plurality of baskets, is maintained stationary. The screens likewise do not rotate but are hinged to fall downwardly out of the way to release the treated material from the baskets. A camming frame structure is rotated beneath the screens in order to sequentially pivot the screens downwardly to open each basket to permit the material being processed to be removed from the baskets. While the screens are in place beneath the baskets, the miscella is collected in a pan which rotates with the camming frame beneath the screens.
This system, however, requires a plurality of rollers associated with each of the pivoting screens, which ride on the camming frame, as well as requiring all of the hinges and associated hinge pins for each screen, which all tends to complicate the device and therefore requires an undesirable amount of labor to keep the equipment operational. However, this type of device does have an advantage over that previously described, in that the material being processed is maintained stationary during treatment so that the fines are generally not released into the miscella to the extent that occurs when the baskets are rotated.